Straight hole drill collar



Feb. 20, 1951 E. STEWART ET AL STRAIGHT HOLE DRILL COLLAR Filed Sept. 10, 194E INVENTORS LEONARD E. STEWART MARVIN J. WINTERS .ATTOQNEYS Patented Feb. 20, 1951 OFFICE STRAIGHT HOLE DRILL COLLAR Leonard E. Stewart, Midland, and Marvin J. Winters, Odessa, Tex., assignors to Noble Drilling Corporation, Tulsa, Okla., a corporation Delaware 7 Application September 10, 1949, Serial No. 115,066

4 Claims.

This invention relates ment.

In drilling oil well holes with conventional equipment, such as that in use prior to the present invention, the use of heavy weight on the 7 cutting tool is relied upon to achieve the desired to offset part or most of the weight of the drill collar. This, in turn, reduces the speed of cutting and, when the chert or other hard formation is very thick, may extend for many hours or days the length of time needed to drill a hole to the producing formation.

Y .A drill collar according to thepresent invention is capable of cutting under full weight, and at full speed, through hard and sloping formations, such as chert, of great thickness, without appreciable or excessive drift, and thereby to enable holes to be drilled through such formations in a materially'shorter number of hours or days than has heretofore been considered possible. In the drawings annexed hereto Fig. l is a vertical section through a well drilling in a hard rock formation, illustrating an arrangement embodying the invention;

Fig. 2 is a fragmentary vertical elevation of the improved drilling equipment;

Figs. 3 and 4 are transverse sections taken respectively alonglines 3-3 and 4' l of Fig 2, each being viewed in the direction of the arrows;

" Fig. 5 is an enlarged partial longitudinal section taken along line 5-5 of Fig. lbeing in part broken away; and,

Fig. 6 is a transverse section 66 of Fig 5.

Referring to the drawing, l6 denotes a well hole that is being drilled in hard rock formation, for example, chert II by a drillbit l2 which is rotated-by means of a drill collar. This collar has aportion l3 in which the drillbit is secured. A portion !4 of the drill collar of somewhat larger diameter than portion !3 adjoins the latter and is provided in its face with longitudinal recesses taken along line to oil well drilling equ p- 2 ameter is substantially equal to the outside diameter of the bit [2 when new. A circumferential fixed abutment portion I la of the drill collar adjacent the portion M has a larger diameter than portion l4 but less than the outside diameter of bit l2. An intermediate or sleeve-rcceiving portion ll of the drill collar adjoins the fixed abutment portion Ma, being less in diameter than said portion [4a and defining a shoulder l8 therewith. Q

A substantially cylindrical sleeve I9 is slidably and rotatively borne on the intermediate portion ll of the drill collar. This sleeve has substantial length being of the order of 8 to 20 feet. The

outside diameter of sleeve 19 is smaller by'asmall percentage than that of a fresh bit l2.

v By way of example only, if the outside diameter in which conventional reamers It are removably positioned. Preferably these reamers It are 9 d me n t t e. m xim m ami 9 total cylindrical surface.

of a fresh bit I 2 is 8% inches, the outside diameter of sleeve [9 is approximately 8 inches. The opposite ends of sleeve l9 taper inwardly. Several shallow grooves extend parallelly and longitudinally in the outer surface of sleeve l9. In the embodiment shown, six grooves 29 spaced apart equally at approximately 60 from each other are provided. The peripheral surfaces 2! between each two adjacent grooves is approximately 50 in width so as to present an extensive cylindrical outer surface interrupted only by the grooves which comprise a minor portion of the The inner diameter of sleeve i9 is somewhat larger than the outervdiameter of portion IT on whichit is longitudinally slidable. A plurality of equi-spaced openings or holes 22 extend through the wall of sleeve I9 providing communication between its outer and inner surfaces to permit a flow of fluid for clean:- ing purposes as will be described.

The intermediate portion ll of the drill collar is threaded externally at 24 and extended be:- yond the threaded portion is a portion 25 "of slightly reduced diameter. A threaded nipple 26 is provided on the end of portionl25 for attachment of the lowest drill pipe. An internally threaded retaining collar or locking nut 21 freely slidable on portion 25 is screwed onto the threads 24 providing an upper stop or shoulder 21a for the sleeve 19. This shoulder 21a is spaced apart from the shoulder l8 adistance sufficiently in excess of the length of sleeve I9 to, provide as?- proximately a two foot longitudinal travel slide of the sleeve IS on portion ll, for purposes-presently to be described.

The retaining collar 21 is suitably locked in its position on the threaded portion 24, for ex? p e. y he t ve se y. e endinsk ys 23 and locking pins 30. Any other conventional locking arrangement may be provided.

Operation the reamers l6, and upwardly through the passages defined by grooves 21) of sleeve {9 and the walls of well l0. Some of the wash water enters the holes 22 flowing in the ,clearance betweenthe inside diameter of sleeve l9 and outer diameter of pipe portion I 1 to wash out any clogging matter, All drilling cuttings eventually are washed out of ,themouth of the well. The reamers .16, which are filatively close to the bit and which wear out much more slowly than the bit l2 itself, maintain the desired Well diameter notwithstanding reduction of the bit diameter at a, more rapid rate as a result of wear in the drilling operation.

The sleeve. [9 is spaced approximately 4 feetfrom the top of the bit 12. If, due to a hard sloping formation, the bit tends to drift, this .tend ncy is counteracted by the sleeve l9 whose smooth cylindrical surfaces 2| bear against the well wall and guide the bit in a straight path without, however, preventing rotation of the drill collar in; "time the bit la. The sleeve is .then functions as a vertical guide for the ,drill collar and-the bit l2 and either prevents drift entirely or reduces it to an inconsequential amount. In-jasmuch as the reaming diameter of the reamers l6 maintain the required well diameter, and this is slightly larger than the diameter of the cylindrical surfaces of the sleeve, the lower end of sleeve [9 will ordinarily follow fairly close to the bit because the .cylindrical surfaces of sleeve 19 are slightly smaller than the well diameter.

Under ordinary conditions, as for example in soft formation where there is less tendency to drift, the cutters l2 may be placed under very heavy weight and drilling will proceed at a rapid rateJ In all drilling, it is noted that cutters such as l2 tend to wear down rapidly, and as. they become Worn they cut a hole of less than desired size. On the other hand, vreamers .lli maintain their size for a much longer period of time, often lasting as long .as three cutters. In soft formations the sleeve 19, being slightly smaller in outside diameter than the reamers l6, slides frely in the hole and rests against th lower stop i8. When our drill strikes a very hard and sloping formation, tending to cause the cutters to drift, th upper end of sleeve 19 comes in contact with the-internalwall of the hole and, by reason of its length, serves as a guide to hold the cutters [2 in a straight path. In performing this function, the very slight clsarance between the outer cylindrical surface of sleeve (9 and the internal wall of the hole, and the fact that the major portion of the outer surface of sleeve 19 is of a smooth cylindrical form, nables the drill as a whole to be kept under heavy weight and to continue cutting without loss of speed other than -tlie"slowing-up due to the harder stone "being drilled. We have found that full weight can be maintained on our drill while passing through sloppingchert, and that the drill will go through the chert-withoutprohibitive drifting.

LCM

A further advantage of the smooth cylindrical outer surface of sleeve I9 is that it has a minimum tendency to become wedged or stuck in the hole. In order to facilitate loosening of the sleeve, if this happens, we provide a substantial clearance between each end of sleeve IS and the abutments I8 and 21a aggregating, in the example here shown, about two feet. If the sleeve becomes wedged or stuck, w continue drilling until abutment 27a comes in contact with the upper end of sleeve [9. Then the drill collar as a whole is "hauled rapidly upward at increasing speed till abutment It strikes the lower end of sleeve [9. Flor this purpose we prefer a free movement of about two feet, which is sufiicient to enable the drill collar to be moving upward, at the moment ,of contact, with sufficient momentum to free sleeve 19 from any frictional contact with the hole likely to be encountered in practice. When it becomes necessary to free sleeve 19 in the manner just discribed, the fact :.of 'its, substantial length, plus the fact that it possesses an outer surface of which a major'part is smoothwa'nd cylindrical, prevents the sleeve from looking or digging itself into the wall of the hole, and enables it to be readily freed even in the hardest formations. v

The following is by way of example, in order to illustrate our invention. We have drilled a hole of 8%" diameter with a drill as herein described to a depth of several thousand feet. The drill collar assembly was of sufficient weight to permit about80,0ll0 pounds to be placed upon the cutters and at no time was this weight reduced.

This drill maintained an average speed of drill ing of about 20 feet per hour through a series or formations including a deep bed of chert, with an average drift not exceeding degree. A conventional drill, of the kind heretofore in use, operating side-by-side with the drill above mentioned and passing through the same formations, on encountering the chert had to be lightened till the weight on the cutters was reduced to about 10,000 pounds, and it then cut at the rate of only about 3 to 4 feet per hour. Even with portion intermediate the length of theicollarand of larger outside. diameter than the first-mentioned portion, and a third portion adjacentithe other end of the collar and being of larger outside diameter than the second-mentioned portion and separated therefrom by a fixed circumferential abutment, screw threads in that end of the intermediate portion which is adjacent the first-mentioned portion, a locking nut adapted to be freely slidable upon the first-mentioned portion and to engage the threads of the intermediate portion, a sleeve slidable upon said intermediate portion and adapted to be moved'lon gitudinally thereof in a path of travel determined by the engagement of itsends with said abutment and saidnut respectively, and reamer cutters mounted upon said third-mentioned portion defining a radius of action slightly larger than the radius of said sleeve.

2. A drill collar as specified in claim 1, wherein the sleeve has a plurality of shallow longitudinal grooves extending the entire length of its outer cylindrical surface, the said grooves being separated from one another by smooth curved surfaces constituting longitudinal segments of a cylindrical surface, the said smooth curved surfaces constituting the major part of the area of the entire outer cylindrical surface of said sleeve.

3. A drill collar as specified in claim 1, wherein the sleeve has a plurality of shallow longitudinal grooves extending the entire length of its outer cylindrical surface, the said grooves being separated from one another by smooth curved surfaces constituting longitudinal segments of a cylindrical surface, the said smooth surfaces constituting about of the area of the entire outer cylindrical surface of said sleeve.

4. A drill collar as specified in claim 1, wherein the sleeve has a plurality of shallow longitudinal REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 20 1,773,231 Lawrence et a1. Aug. 19, 1930 1,844,371 Santiago Feb. 9, 1932 2,177,300 Kellegrew Oct. 24, 1939 2,501,025 Burris Mar. 21, 1950 

